Background Timekeeping is one of humanity's earliest sciences. Long before modern clocks and calendars, ancient Indians observed the movement of the Sun, Moon, and stars to measure days, months, and years. This led to the creation of Panchanga the traditional Indian calendar, which combines solar and lunar cycles to mark festivals, agricultural activities, and religious events. Unlike the Gregorian calendar, which is purely solar, the Indian calendar is lunisolar it adjusts months and years using astronomical calculations to align with seasonal changes. Ancient scholars such as Aryabhata, Varahamihira, and Bhaskaracharya contributed to these systems using keen observation and mathematics. Understanding the Indian calendar reveals how science, culture, and environment are interlinked. This project encourages children to explore astronomical observation, mathematical reasoning, and traditional knowledge-blending the wisdom of the past with the scientific curiosity of the present. Hypothesis If we study the principles behind the Indian calendar system and compare them with the Gregorian calendar, we can understand how ancient Indian scientists used astronomy and mathematics to develop a more nature-linked and precise method of timekeeping Objectives To study the structure and components of the Indian calendar system (Tithi, Nakshatra, Yoga, Karana, Vara). To compare the Indian (Panchanga) and Gregorian calendars in terms of month length, leap years, and seasons. To understand how astronomical events like solstices, equinoxes, and lunar phases influence the Indian calendar. To explore local festivals or agricultural practices linked with the Indian calendar. To promote awareness of India's scientific heritage in time measurement. Methodology Literature Study: Collect information from books, Panchangas, and online sources on Indian and Gregorian calendars. Observation: Record sunrise, sunset, and moon phases for one month and compare with Panchanga predictions. Data Comparison: Create charts showing differences in months, leap year adjustments, and important dates between the two systems. Interview: Talk to local priests, astronomers, or farmers about how they use the Indian calendar for festivals or crop timing. Model Creation: Make a simple visual or 3D model showing the movement of the Earth, Moon, and Sun that defines Tithis and months. Expected Outcomes Children-scientists will understand how the Indian calendar connects astronomy, agriculture, and daily life. They will be able to explain why the same festival (like Diwali or Holi) falls on different Gregorian dates each year. The project will demonstrate that ancient timekeeping was based on scientific observation, not superstition. Children-scientists will appreciate the precision and sustainability behind India's traditional systems. Significance This project bridges science, culture, and environment — showing that India’s traditional knowledge systems were rooted in observation and logic. It helps children realize that Indian astronomers were early scientists who linked human life with natural cycles. By exploring the Indian calendar system, students not only rediscover cultural heritage but also learn how astronomy shapes time, seasons, and festivals. This understanding nurtures scientific temper, curiosity, and respect for traditional wisdom - aligning perfectly with the Children’s Science Congress theme of “Lifestyle for Environment and Sustainability.” Source : Science and Innovation for Sustainability - Activity Guide Book 2026 & 2027